全然~ない (not at all)

The adverb 全然 combined with a negative predicate, meaning 'not at all / not in the slightest.' Very common in colloquial speech to strengthen a negation. 全然分からない ('I don't understand at all'). Modern colloquial Japanese also uses 全然 with positive predicates (全然大丈夫 'totally fine'), a usage once considered incorrect but now widespread in casual speech. The kanji form 全然 is standard; kana ぜんぜん is a colloquial variant.